Also recognize __sighndlr on Solaris/x86

Unlike Solaris/SPARC, the __sighndlr function isn't recognized as part
of a signal handler, causing a couple of testcases to fail.

The following patch fixes that.  A followup patch will move this to
common code to avoid such unnecessary discrepancies between
Solaris/SPARC and x86 in the future.

While this fixes a couple of backtraces to now correctly print

#1  <signal handler called>

they often fail later with

#2  0x0ff3ffffff00857f in ?? ()
Backtrace stopped: Cannot access memory at address 0xff3000002e0886f

which needs further investigation.

Tested on amd64-pc-solaris2.11 (running the tests with both -m64 and
-m32).

	* amd64-sol2-tdep.c (amd64_sol2_sigtramp_p): Also recognize
	__sighndlr.
	* i386-sol2-tdep.c (i386_sol2_sigtramp_p): Likewise.

gdb/ChangeLog

@@ -1,3 +1,9 @@
+2018-09-23  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>
+
+	* amd64-sol2-tdep.c (amd64_sol2_sigtramp_p): Also recognize
+	__sighndlr.
+	* i386-sol2-tdep.c (i386_sol2_sigtramp_p): Likewise.
+
 2018-08-02  Jon Turney  <jon.turney@dronecode.org.uk>
 
 	* windows-nat.c (windows_nat_target::wait): Remove a spurious

gdb/amd64-sol2-tdep.c

@@ -74,7 +74,8 @@ amd64_sol2_sigtramp_p (struct frame_info *this_frame)
 
   find_pc_partial_function (pc, &name, NULL, NULL);
   return (name && (strcmp ("sigacthandler", name) == 0
-		   || strcmp (name, "ucbsigvechandler") == 0));
+		   || strcmp (name, "ucbsigvechandler") == 0
+		   || strcmp (name, "__sighndlr") == 0));
 }
 
 /* Solaris doesn't have a 'struct sigcontext', but it does have a

gdb/i386-sol2-tdep.c

@@ -57,7 +57,8 @@ i386_sol2_sigtramp_p (struct frame_info *this_frame)
 
   find_pc_partial_function (pc, &name, NULL, NULL);
   return (name && (strcmp ("sigacthandler", name) == 0
-		   || strcmp (name, "ucbsigvechandler") == 0));
+		   || strcmp (name, "ucbsigvechandler") == 0
+		   || strcmp (name, "__sighndlr") == 0));
 }
 
 /* Solaris doesn't have a `struct sigcontext', but it does have a